Principal DevEx Engineer

Femtech Insider Ltd.; Greater London; Hybrid; GBP 120,000 - 180,000; Full time

Benefits offered by this job

Competitive salary and annual reviews

Performance incentive scheme

Paid holiday and sick leave

Parental leave and family health leave

Learning support and growth

Job summary

Flo seeks a senior Platform Engineer to own and evolve our core cloud stack. You will build self-serve tooling for product teams, manage AWS/EKS/Terraform-based platforms, and guide reliability initiatives at a global scale.

You will lead on-call, privacy-focused infrastructure, and end-to-end observability, collaborating across distributed teams and driving security-first engineering practices.

Qualifications

• 15+ years in AWS infrastructure, DevEx, SRE or DevOps for high-traffic systems.
• Deep expertise in AWS and Kubernetes (K8s).
• Automation mindset with Terraform; coding in Python, Scala or Go is a plus.
• Comfort with full-stack scope from front-end with React to infrastructure abstractions.
• Strong documentation and cross-team collaboration.

Responsibilities

• Develop self-service tooling enabling product teams while preserving system stability.
• Architect and evolve the core stack (AWS, EKS, Terraform).
• Lead reliability initiatives and a sustainable on-call rotation.
• Support high-scale privacy features and infrastructure such as Anonymous Mode.
• Implement best-in-class observability across metrics, logs, and tracing.

Skills

AWS Infra

DevEx/SRE/DevOps

Kubernetes

Terraform

Python/Scala/Go

React

Documentation

Communication

Tools

Sentry

Job description

500M+ downloads. 80M+ monthly users. A decade of building – and we’re still accelerating.

Flo is the world’s #1 health & fitness app worldwide on a mission to build a better future for female health. Backed by a $200M investment led by General Atlantic, we became the first product of our kind to reach a $1B valuation in 2024 – and we’re not slowing down.

With 7M paid subscribers and the highest-rated experience in the App Store’s health category, we’ve spent 10 years earning trust at scale. Now, we’re building the next generation of digital health – AI-powered, privacy-first, clinically backed – to help our users know their body better.

The job

The Velocity team exists to eliminate friction. We treat our internal developers as our customers. You will:

• Abstract Complexity: Build intuitive tooling that enables self-service allowing devs to focus on product logic.
• Standardize Excellence: Bake best-practices, security, observability, and scalability into the core stack so they aren't afterthoughts.

What You Will Do

• Developer Experience: Build self-service tools that give product teams autonomy without sacrificing system stability.
• Platform Engineering: Architect and evolve our core stack (AWS, EKS, Terraform).
• Systems Resilience: Lead reliability initiatives, including business continuity planning and a sustainable on-call rotation.
• High-Scale Privacy: Support the infrastructure for industry-leading privacy features, such as our TIME-recognized "Anonymous Mode."
• Observability: Implement best-in-class monitoring (metrics, logs, tracing) to ensure issues are identified and mitigated before they impact the user.

What You Bring

• Experience: 15+ years in AWS Infrastructure, DevEx, SRE, or DevOps roles supporting high-traffic, distributed environments.
• Cloud Native Mastery: Deep expertise in AWS and Kubernetes (K8s) is essential.
• Automation Mindset: Proficient in Infrastructure as Code (Terraform), a coding background with experience with Python, Scala or Go would be beneficial.
• Technical Breadth: You will feel comfortable at all levels of the stack, from developing front ends using React through to engineering Terraform modules to deliver infrastructure abstractions.
• Communication: A "doc-first" mentality and the ability to collaborate across distributed product teams.

AI First: You will have experience of the impact which AI automation is having on development teams and the software delivery lifecycle and have strong ideas on how to support them through it

Bonus Points

• Background in hardening infrastructure for high-compliance or security-sensitive environments.
• Experience scaling consumer tech platforms with millions of concurrent users.
• Professional Accreditation such as AWS Professional Architect, CKAD or KCSA.

Why Join Flo?

• High Impact: Flo is re-writing women’s health.
• Autonomy: We hire experts and empower you to deliver.
• Cutting-Edge Stack: Work with modern tools like Sentry, EKS, and Terraform in a fast-paced, "fail-forward" environment at a huge scale.

How we work

We’re a mission-led, product-driven team. We move fast, stay focused and take ownership – from brief to build to impact. Debate is encouraged. Decisions are shared. We care about craft, ship with purpose, and always raise the bar.

You’ll be working with people who take their work seriously, not themselves. It takes commitment, resilience, and the drive to keep going when things get tough. Because better health outcomes are worth it.

What you'll get

We support impact with meaningful reward. Here’s what that looks like:

• Competitive salary and annual reviews
• Opportunity to participate in Flo’s performance incentive scheme
• Paid holiday, sick leave, and female health leave
• Enhanced parental leave and pay for maternity, paternity, same-sex and adoptive parents
• Accelerated professional growth through world-changing work and learning support
• In-person collaboration and work in a hybrid model, with 3 days per week spent in the office
• 5-week fully paid sabbatical at 5-year Floversary
• Flo Premium for friends & family, plus more health, pension and wellbeing perks

Diversity, equity and inclusion

Our strength is in our differences. At Flo, hiring is based on merit, skill and what you bring to the role – nothing else. We’re proud to be an equal opportunity employer, and we welcome applicants from all backgrounds, communities and identities. Read our privacy notice for job applicants.